Just wanted to put up a reminder about spontaneous combustion.
I've been replacing the flooring on my deck. Today I was out staining the boards before installing them. I painted on the stain, the used a paper towel to wipe off the excess. As I was doing the last few boards my daughter came over and was talking with me. I finished the staining and was cleaning up. I had accumulated a fairly large pile of stain soaked paper towels. I decided it was a good time to warn her about the possibility of spontaneous combustion with these rags, so we had a little talk about if she ever stains or paints, not to leave the rags laying around. I gathered up all the paper towels and put them in the chiminea. Since it's designed to have a fire in it, I figured it's a good place to put them.
About 2 hours later my daughter said she was smelling a funny smell. I barely noticed it, but it smelled like stain. The sliding door to the porch was open and I had been staining just outside so figured that was what it was. I went out and the smell was stronger. Looked around - everything was fine.
10 minutes later I asked my son to come out and help me rip up some more floor boards. Again - everything looked fine - the chiminea was just sitting there. We ripped off the first board and I look over and white smoke was pouring out of the chiminea! I called over my daughter who couldn't believe it. For 5 minutes it sat there with smoke pouring out of it. I sent my son in to get a lighter - figured I'd just light it and get it over with. While he was gone I went over and blew on it and it almost exploded in flames. The flames were coming out the side and shooting 3 feet in the air over the chimney. I probably burned for 15 minutes.
So remember, anytime your using stain, or paint, or mineral spirits, or linseed oil, there is a chance that the rags can spontaneously combust. Please dispose of them properly.
Won't oily rags of any kind do that, just not as fast? OSHA wants my shop to put the used, oily rags in an open metal drum when waiting for the laundry guy to pick them up.
I know of farmers barns that burning because they put wet hay in their haymow .
"I probably burned for 15 minutes". Bet that hurt.
ANY TYPE OF OIL OR GREASE WILL. I used to work for a laundry and many times I would get a call from the Fire Dept that they had knocked the door down to answer a fire call in the sorting area. It got so bad I told them that a window in the shop would be unlocked just for them. The worse was napkins from restaurants that had grease on them. Dan
I will say it again, In about 1959 working in a high end custom furniture shop the German cabinet maker warned me about spontaneous combustion. He took a rag soaked with Watco it has linseed oil in it. Any thing that has linseed oil in it is dangerous for spontaneous combustion.
He put the rag waded up out in the sun on a warm day in less then an hour it was smoldering.
My trade for many years was disaster restoration. usually on a warm day several fires would happen over that issue. I seen some tragic ones!
The MSDS Sheet for Biodiesel warns of the same thing.
I could go on about Biodiesel, but there aren't many diesel burners here.
May, 1890. A.A. Newman, prominent Arkansas City merchant, is having a new house built. Painters leave rags in the third floor ballroom and spontaneous combustion burns the place to the ground.
All you have to do is ask yourself,"If I was going to have a fire with these rags, where would I like it to be?" Usually that is outside in a metal container, far away from everything of value. Works everytime for me..
I always had the impression that the cotton in rags played into the chemistry of it. Obviously not, as I see here. What is the cause?
It's caused by the oxidation of the oily mixture, which generates heat. Let's say if you apply boiled linseed oil to a cotton rag, when linseed oil is exposed to air, it combines with the oxygen molecules. This chemical reaction creates heat. If the linseed oil is on something like a cotton rag, it can catch fire 120 degrees -- with no outside spark.
It is interesting that we have this thread at the same time there are a couple discussions going on about the danger of "sitting on the gasoline tank".
Much like an "early" model T engine block can be a genuine original open valve block, or a "fake" one. Or maybe that "early" block is a real 1913, or a 1918 made to look like a '13, or a genuine 1917 just how it is supposed to be.
That block could be worth ten thousand dollars. Or it might be worth fifty dollars, or anywhere in between. The devil is in the details.
The fire hazards of gasoline need to be understood, and the potential danger respected. Sitting upon the gasoline tank should not be feared. Liquid gasoline is not very volatile. It must have an air (oxygen) mixture to ignite and burn. There are circumstances that can ignite gasoline inside a tank, but they are rare.
Spontaneous combustion of a combination of materials is a bit different than liquid gasoline. Almost any sort of (even marginally) burnable rag, paper, or bio-mass can hold almost any sort of burnable oil, wax, thinner, or alcohol, in a sort of suspension. This allows air pockets to form all around and within suspended fuel. It is very much like that gasoline vapor in an air mixture. sort of in a static (non-moving) form.
A small amount of heat (sitting in the sunlight is more than enough) will agitate the chemicals a bit. That agitation will result in some small amount of oxygenation of the burnable chemicals present. Then something really interesting (for lack of a better word) happens. Because the rags and /or etc are stationary (or static), they also act as insulation. The heat generated by minor oxygenation of chemical does not dissipate quickly. The insulation effect raises the temperature, the raising temperature increases the oxygenation of chemical which in turn again raises the temperature, and a cycle is born. IF, and it is a huge IF, the oxygen within the static unit is used up before a real burn is begun, it will likely burn out. That is why some people have wondrous tales of finding the cold hole burned onto the floor, but no fire.
On the other hand, that huge IF again, IF fuel and oxygen hold out long enough, it will get hotter and hotter until it bursts into flame. If you find the pile smoking, but no flame, moving it with a stick or blowing on it will often result in flaming up very quickly because the pockets of fuel were oxygen starved and stirring it up or blowing on it just provided a fresh supply of air. I have had the opportunity and done that several times.
Different chemicals have different flammability characteristics. They also have different characteristics for forming those air/fuel pockets which changes the requirements for spontaneous ignition.
I understand that linseed oil is one of the worst chemicals, soaking so perfectly throughout the fibers of a rag that it can self-ignite in an ambient temperature of less than 100 degrees Fahrenheit.
I once had a steel garbage can full of fresh-cut lawn grass reach a temperature near 200 degrees. I figured with the tight fitting lid, it would use up the oxygen inside. Moved the can to the middle of the yard, away from anything, and put a concrete block on top of the lid, then kept an eye on it. A couple hours later, it had cooled off, but wow did it stink when I lifted the lid a couple days later.
Fire is amazing stuff. People fear it often when they shouldn't. Then they do things that have a very serious danger potential, because they don't understand it.
That is why threads and reminders like this are important.
Thank you David S! It sounds like you handled a "teachable moment" perfectly.
I never worry about sitting on the gasoline tank. I am nearly paranoid about rags or paper towels soaked in any sort of oil based anything.
Do drive carefully, and enjoy, W2
In about 1985 the original Pentolten woolen mills home burned in Portland from a floor refinisher leaving rags in an open can at the top of the staircase on a warm day. The cost of just the refinish of that old staircase was 35k as I remember.
So, what is the best way of disposing with wet oily rags or paper? I have thrown them on the driveway in the sun to evaporate for a few days before throwing in the dumpster. But some have said that is a bad thing to do. I have thought placing the wet rags into the dumpster would cause everything in the dumpster to burn. However, I don't want to keep them in the garage for fear the garage will burn?
What should I do with them? Would putting them in a bucket of water be a good or bad thing?
So far I have worked on cars, and painted things for over 70 years without a spontaneous combustion, but maybe, I have just been lucky!
Here's what the state of Massachusetts says about the subject:
There are special containers for holding oily rags:
That article seems to focus on paint/varnish type substances that probably contain linseed oil. The above discussions seem to point at ANY oily rag. I have to admit, I have never taken any precautions with anything other than linseed oil or linseed oil products. Will a paper towel that you wipe your hands off on after packing a wheel bearing suddenly burst into flames? I've never heard of it, but that doesn't mean it isn't so. I've heard the precautions about linseed oil products all my life, but only recently, have I heard anything about motor oil or cup grease or paper napkins. Can I really wipe the Colonel Sanders off my hands onto a napkin and it burst into flames in the trash can?
Motor oil, lubricating grease and such do not spontaneously ignite. Oil- based paints and stains, varnishes and polyurethane, paint thinners, etc are a problem.
If in doubt I always throw them in the shop wood stove. They will cause a problem there.
You and me both Jim.
So if oily rags don't self ignite why do state and maybe federal laws tell us we need to put oily rags in the proper container, IE the ones with self closing lids painted red in a shop environment?
I hope I'm not off topic here. When I was a teen, I worked at a plastics plant. Someone took a blob of warm plastic about the size of a Model T engine out of a machine and put it on the floor. Later a supervisor noticed it was getting hotter and he moved it outside to the loading dock area so it could cool down. Within an hour, the loading dock area and roof were fully ablaze.
My life time career was a fire investigator and spontaneous ignition happens in several forms. The usual type as per discussion involves vegetable products of some form specifically linseed oil is top of the heap for spontaneous ignition. It does not require the temperature to be elevated it can do it by itself at room temperature. Mineral oil will not self ignite ie car oil and grease only vegetable oils will self ignite and there is a large number of varities of vegetable oils and blends so the variables are endless. The next most common mixture is cooking oil, cotton (as in cotton mop) and bleach which is a common mixture in restaurants, however said mixture requires a kick start usually hot water. When a cotton mop is used to wipe up spilled oil at KFC and the mop is placed in a bucket of hot water and bleach and the mop placed out side to drip dry will usually violently self ignite. I have investigated several restaurant fires where this has happened. Additionally cotton and linen towels,apons and wipers contaminated with cooking oil will not usually self ignite except when placed in a commercial dryer where the temperature is elevated. Cleaning materials that do not contain vegetable products will not self ignite. There Is a third method where self ignition can occur, that is chemical mismatches like products under the sink. People have a host of potential under there there are many under the sink fires. Dry hay or grass will not self ignite however add some moisture and look out. Your damp lawn grass can seriously burn your hands, I measured the temperature it reached 140F. The reason the Fire service says to place all oily rags in a metal container is because there are so many variables, to explain all the variables would take many pages. I have 40 years of stories but I have to stop here.
Very interesting post for me David--- Thanks!
Thanks David. It's good to know the sky isn't really falling and I haven't just been lucky all these years.
They say you can't be too safe, but sometimes I wonder. I've seen it many times in industry. Large corporations are the worst. OSHA has a reg which may or may not already be over the top. Some corporate safety person who was appointed to the position because he was incompetent at other things makes his interpretation of the OSHA reg and makes it corporate policy. Then it trickles down to the plant level where their incompetent safety guy makes his interpretations and additions and before you know it, it's a wonder any of us have ever lived to be adults as careless as we must be.
The one item that wasen't mentioned was dog poo.
It will burst into flames if it is placed in a paper bag!
This always seems to happen when it is placed on a grumpy old mans front porch around Halloween time.
Hal, A friend now past was head of safety at the gas company. A female OSHA inspector wrote up a hefty fine for the shop using a nail of the right diameter in place of a cotter pin on a cherry picker. I forgot now what he said it cost for an engineer to prove the nail was stronger then the cotter pin!
If I don't have a safety can handy, I take whatever rag/cloth/paper I have used, open it out flat and lay it on concrete, or outside to dry out for a day or so, then I throw it away.
I THINK that's a safe method. . .
That is exactly the procedure recommended on my can of boiled linseed oil and is the one I follow....for linseed oil. Motor oil? Rag lays around until it is too dirty to any longer clean my hands, then goes into the trash can.
I too lay all my oil, grease, paint thinner, and paint stripper rags out on the driveway spread out so they can dry before I put them in the dumpster. I will not place any rags in the dumpster the same day they are used. I wait at least 24 hours. One time I balled them up and laid them out just to see how long it would take to smolder or burn. It only took a little over an hour for the paint thinner rags to start to smolder out in the sun light.
Even after reading these posts that appear here on a regular basis I had the same thing happen in my workshop.
We are building a new house on the same location as our old one and we have 2 garages on our property, a small workshop and a big garage where we keep our cars.
For 4 days I could smell smoke like a campfire in the workshop, first day I looked around, nothing was obvious, the second day my wife was there and she said it smelled like oil, third day could still smell it, finally the fourth day I laid a glove down on the smouldering rags that were in the box pictured with a set of connecting rods and discovered the cause. The rag had Varsol on it.
I couldn't believe it, now I am a bit on the paranoid side instead of just careful.
Not spontaneous but an unexpected fire never the less.
While working as my position as Signal Maintainer for the RR the Signal crew was changing some signal lights to LED style and asked me if I'd like to have the old lenses and reflectors for spares. I said sure, I'll take a few. So they left them in a cardboard box outside next to my office door. The sun came up over the hill and shone on one of the mirrored reflectors, yup you guessed it the sun reflecting off the concave shaped mirror ignited the cardboard box! It charred the siding on the building before a quick thinking neighbor saw it and put it out.